They say eating too much is “israf” which means, “waste” or “squandering” …
It is important to understand that the concept of waste here is not in reference to the food that is eaten but the one who is doing the eating!
This is because the brain and other organs need a specific amount of energy to function. Excess energy is of no use to them at all; in fact, the brain has to work harder to convert this excess, which it doesn’t even need. Plus, this stock of useless energy creates an extra ‘cavity’ in the brain, in terms of the energy the brain ends up wasting away.
Nobody can harm the brain of an overweight person more than the harm he causes to himself!
The dhikr that is done while one is fasting, on the other hand, produces a lot more energy than while not fasting. Hence the Rasul of Allah (saw) excessively praises the act of fasting and is known to have fasted very frequently.
Talking of the harm extra weight causes to the brain, we can’t not cover the topic of alcohol and smoking!